October 1973: a 9-year-old boy, cloistered in a Bangkok compound, flips on the television. No cartoons for him. Instead, the box broadcasts images of Thai students and workers flooding nearby streets to protest the autocratic generals ruling their nation. The boy finds the scenes enthralling, sparking a political awakening unusual in any kid, much less the scion of a privileged Thai-Chinese family. Just three years later, a violent military crackdown would bring this brief experiment in Thai democracy to an end. But by that point, the boy, Abhisit Vejjajiva, was studying overseas in Britain. "I experienced the optimism of...